They have no reason to think otherwise, because science has such powerful explanatory power, and mathematical equations do not have a “God” variable, or as they would disrespectfully put it, there is no place in science for goddidit. Their disrespect is not entirely unwarranted because of some of what comes out of YECism, and OEC has to implicitly involve poofing, not that God cannot.
It also harks back to the argument that God does not want scientific proof of his existence, not that there is not scads of evidence pointing to him and implicitly declaring his power and beauty! Scientific proof of ID would be just that, scientific proof of the existence of a Designer, and I think there are theological reasons why that will not happen, let alone scientific ones.
Proof would negate faith, and it also negates love.